Calculator system having a precharged virtual ground memory

ABSTRACT

Disclosed is a calculator featuring a virtual ground permanent store instruction memory for storing and providing instruction words. The memory cells are arrayed in rows and columns which are respectively responsive to row and column address circuits. Each bit of the instruction word is outputted on a single output line, and a pair of output lines have only one ground line selectively coupling each to circuit ground. The row and column lines are precharged by decoupling the ground lines from circuit ground and precharging the respective output lines, with the column address circuitry coupling each column line to the respective output line for precharging all columns.

United States Patent 11 1 I 1111 3,916,169

Cochran et a1. Oct. 28, 1975 CALCULATOR SYSTEM HAVING A 3,798,617 3/1974 Varadi et al. 340/173 R PRECHARGED VIRTUAL GROUND 3,801,964 4/1974 Palfi et a1 340/173 R MEMORY Primary ExaminerMalco1m A. Morrison Assistant Examiner-Jerry Smith Attorney, Agent, or Firml-laro1d Levine; Rene [75] Inventors: Michael J. Cochran, Richardson;

Charles P. Grant, Jr., Dallas, both of Grossman; Thomas G. Devine [73] Assignee: Texas Instruments Incorporated,

Dallas, Tex. 57] ABSTRACT [22] Ffled: Sept 1973 Disclosed is a calculator featuring a virtual ground [21] A l N 396,901 permanent store instruction memory for storing and providing instruction words. The memory cells are arrayed in rows and columns Which are respectively responsivc to rowand column address circuits. Each bit of the instruction word is outputted on a single output line, and a pair of output lines have only one ground line selectively coupling each to circuit ground. The row and column lines are precharged by decoupling [52] US. Cl. 235/156; 340/172.5; 340/173 SP [51] Int. Cl. G06F 15/02; G1 1C 17/00 [58] Field of Search 235/156; 340/172.5, 173 R,

340/173 DR, 173 SP [56] References the ground lines from circuit ground and precharging UNITED STATES PATENTS the respective output lines, with the column address 3,611,437 10/1971 Varadi a a1 340 173 SP circuitry p g each column line to the respective 3,613,055 10/1971 Varadi et a1... 340/173 SP output line for precharging all columns.

3,728,696 4/1973 Polkinghom 340/173 SP 3,771,145 11/1973 Wiener 340/173 R 7 Claims, 81 Drawing Figures PROGRAMMER CHIP MEMORY STORAGE PRINTER CHIP SEGM EN T DRIVERS DIGIT DRIVERS "K" LINES KEYBOARD US. Patent 'Oct.28, 1975 Sheet1of63 3,916,169

U.S. Patent Oct. 28, 1975 Sheet20f63 3,916,169

PR OGRAMM ER CHIP MEMORY STORAGE PRINTER CHIP I ARITHME'IIC CHIP BUSY SEGMENT DRIVERS DIGIT DRIVERS "K" LINES KEYBOARD US. Patent Oct.28, 1975 Sheet4of63 3,916,169

MACH

ZH mm V'Id EGO 93G )ISVIN US. Patent Oct.28, 1975 Sheet50f63 3,916,169

EXT

[2| IDLE U.S. Patent Oct. 28, 1975 12 pranch :1

Branch of Condition=I MSB Relative Branch Address Fig 50 LSB =O=INCREMENT =l=DECREMENT (branch Sheet 6 of 63 MSB LSB

MSB

LSB

Fig, 5b

M0 Flag Operation M1 All Mask M2 DPT M3 DPT 1 MA DPT C M5 LLSD 1 M6 EXP M7 EXP 1 M8 KEYBOARD OPERATIONS M9 MANT M1O NAIT OPERATIONS M11 MLSD 5 M12 MAEX -Ml L MMSD 1 M15 MAEX 1 R0 A N R1 DIN R2 C N RLL Shift A R5 Shift E R6 Shift 0 R7 Shift D R9 CIR R12 AIConstant R13 NO-OP R111 C+ Constant R15 RE-nAdder (Mask LSD) =O=add=shift left =l=sub=shift right MSB LSB

US. Patent Oct. 28, 1975 Sheet7of 63 3,916,169

The following 8 bits effective only if flag operations 7 (fmd) MSB 6 The following 8 bits effective Generate FlagMa-SK only if Keyboard operations when these t bits equal the 4 encoded state I5 bltS =O=SCAN KYBD (NOTE: ENCODED sTATE TIMES ARE +2 FROM ACTUAL STATES) A =l=KT (fma) LSB- =O=KS The following LL bits (flagops) effective only during flagmask: 1 except f 80 E15 5 =O=KR O TEST FLAG A R =O=KQ 1 TEST FLAG B 2 SET FLAG A I I2 3 SET FLAG B 2 =O=KP (fd) 4 ZERO FLAG A MSB 5 ZERO FLAG B I I f l =O=KO 6 INvERT FLAG A g INVERT FLAG B IO 8 EXCH. FLAG A B =O=KN (fb) 9 COMPARE FLAG A B 10 SET FLAG KR 11 ZERO FLAG KR F/g, 12 COPY FLAG B-A LSB f 13 COPY FLAG A-B l L REG 5-FLAG A S0 S3 15 REG 5-FLAG B SO S3 Fig 5c US. Patent Oct. 28, 1975 Sheet 10 0f63 3,916,169

L l fi 2Q 4|||\lll US. Patent Oct.28,1975 Sheet11of63 3,916,169

TO DISPLAY ARITHMETIC CHIP I e e 27 2a 2.5 24 23 22 2/ 20 I? /6 /7 6 l l 2345o789/0u/2/3/4 'lllllllllll -Q Fig, 7

U.S. Patent Oct. 28, 1975 F ig. 80

Sheet 12 0f 63 Fig. 8b1

Fi 8b2 Fig. 8b?) Fig. 8b4

Fig. 8b5

Fig. 8b6

Fi 8b? Fig. 8b8

Fig. 8b9

Fig. 8b10 Fig. 8c1

Fig.

Fi 8C4 Fig. 865

Fig. 8c8

Fi 8d1 Fig. 8d2

Fig. 8d3

Fi 8d4 Fi 8d5 Fig. 8d6

US. Patent Oct.28,.1975 Sheet 13 of63 3,916,169

Fig. 802

(SHEE 7 1 IsWfiWW/SWEETVFZFWK? U.S. Patent Oct. 28, 1975 Sheet 14 of63 3,916,169

Fig, 8b 4 DNSK CBEJ ONE GO Aura -10 0/5 37 US. Patent 'Oct.28, 1975 Sheet 15 of63 3,916,169

US. Patent Oct. 28, 1975 Sheet 17 of 63 3,916,169

Fig, 5b?

U.S. Patent Oct. 28, 1975 Sheet 18 of 63 3,916,169

Fig, 808

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1. In a data processing system of the type implemented on at least one semiconductor chip and having a virtual ground, permanent store programm memory for storing and selectively providing instruction words in response to an address signal, the memory comprising: a. rows and columns of memory cells having columns grouped to provide a plurality of bits forming the instruction word, and rows addressable to define the bits of the instruction word; b. one output line corresponding to each bit of the instruction word; c. precharging switch means, connected to the output lines for precharging the output lines; d. transfer switch means for connecting the output lines to the columns of memory cells for precharging all columns; e. row select circuitry, responsive to the address signal, for selectively activating rows of the array; f. column select circuitry, responsive to the address signal, selectively activating a column of memory cells by coupling the substrate potential to the selected column and by coupling the corresponding output line to the selected column; and g. timing means, for activating the precharging and transfer switch means for a first prEdetermined time period and for activating the row and column select circuitry for a second predetermined time period following the first predetermined time period.
 2. The memory of claim 1 wherein the array comprises one substrate potential line per pair of output lines, each substrate potential line being selectively coupled to its respective pair of output lines through a pair of cell columns selected by the column select circuitry.
 3. The memory of claim 2 wherein the substrate potential line is selectively coupled to the substrate potential through a gating element.
 4. The memory of claim 3 further comprising discharge means, connected to the row and column circuitry and selectively coupled to the substrate potential, for discharging the row and column circuitry prior to the first predetermined time period, thereby precharging all rows.
 5. The memory of claim 1 further comprising discharge means, connected to the row and column circuitry and selectively coupled to the substrate potential, for discharging the row and column circuitry prior to the first predetermined time period, thereby precharging all rows.
 6. The memory of claim 5 wherein the row select circuitry comprises gating elements responsive to the address signal for selectively discharging one precharged row.
 7. The memory of claim 1 wherein the row select circuitry comprises gating elements responsive to the address signal for selectively discharging one precharged row. 